BACKGROUND Magnetic compression anastomosis (MCA) offers a simple and reliable technique for inducing anastomoses at any point along the digestive tract. Evidence regarding whether the design of the MCA device influences the anastomosis effect is lacking. AIM To investigate any difference in the side-to-side colonic anastomosis effect achieved with cylindrical vs circular ring magnets. METHODS We designed cylindrical and circular ring magnets suitable for side-to-side colonic anastomosis in rats. Thirty Sprague-Dawley rats were randomly divided into a cylindrical group, circular ring group, and cylindrical–circular ring group (n = 10/group). Side-to-side colonic anastomosis was completed by transanal insertion of the magnets without incision of the colon. Operation time, perioperative complications, and magnet discharge time were recorded. Rats were euthanized 4 weeks post-operatively, and anastomotic specimens were obtained. The burst pressure and anastomotic diameter were measured sequentially, and anastomosis formation was observed by naked eye. Histological results were observed by light microscopy. RESULTS In all 30 rats, side-to-side colonic anastomosis was completed, for an operation success rate of 100%. No postoperative complications of bleeding and intestinal obstruction occurred, and the postoperative survival rate were 100%. The operation time, magnet discharge time, anastomotic bursting pressure, and anastomotic diameter did not differ significantly among the three designs (P > 0.05). Healing was similar across the groups, with gross specimens showing good anastomotic healing and good mucosal continuity observed on histological analysis. CONCLUSION This study found no significant difference in the establishment of rat side-to-side colonic anastomosis with the use of cylindrical vs circular ring magnets.